DMP 120 (260-1255)               Buffer                Faxback Doc. # 4411

PRINTER BUFFER OPERATION

The printer's ability to temporarily store data is one of its main
advantages over a typewriter.  Codes sent to a typewriter (that is, keys
you press) are transferred immediately to the paper.

Codes sent to a printer are not printed immediately; they are stored in a
separate section of memory in the printer called the buffer.  When the
buffer fills, or certain codes are received (that is, LF or CR), the buffer
is emptied and all data is printed on the paper.  What happens after the
buffer data prints depends on the circumstances.  In some cases, printing
continues on the same line; in others, the print head moves to a different
position relative to the paper.

In the CP mode, commands for changing fonts, line feed, and so on, can be
stored in the print buffer until data is printed.

TIPS ON THE PRINTER BUFFER

FOR CP AND GRAPHICS MODES:

* The buffer allocates a fixed number of dots, depending on the character
  width selected.  The buffer empties when the stored data equals that
  number.  Printing resumes at the start of the next line.

* The last character received by the buffer is printed at the start of the
  next line following an automatic line feed and carriage return.

* The next-line code (NL) feature is selected while switch 1 is OFF (down).
  When the buffer is emptied, printing will resume at the start of the next
  line.

* The carriage-return code (CR=13 decimal) automatically activates printing
  (assuming that at least one character code is already in the buffer).  If
  switch 1 is ON (up), Carriage Return (CR) will occur and the next full
  buffer will over-print on the current line.

* The line-feed code (LF=10) automatically activates printing, and the
  Print Head is positioned at the start of the next line.

* If the computer delays more than a second before sending the next print
  code, the buffer prints.  Printing continues from the current position.

CP MODE ONLY:

* If a character set of a different dot density is selected, the data in
  the buffer is printed immediately.

Codes for changing character sets are (27 19) and (27 20).  Printing
continues in the next line with the new character style.

* Dot graphics printing continues from the current character position.

GRAPHICS MODE ONLY:

* When the "End Graphics Mode" command is received, the buffer is printed.

The Printer returns to the CP Mode and printing continues in the same line
from the current print position.

NOTE: In the description, "next line" means the new line reached by
      performing a line feed operation.

(abo-07/26/93)

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